This randomised, double-blind, placebo (PBO)-controlled study evaluated the efficacy and safety of ezetimibe (EZE) co-administered with ongoing atorvastatin (ATV) therapy in 450 hypercholesterolemic patients with coronary heart disease (CHD) who had not achieved their low-density lipoprotein cholesterol (LDL-C) goal < or =2.60 mmol/l while on a stable dose of ATV 10 or 20 mg/day for > or =6 weeks. After a 4-week diet/baseline active run-in period, patients with LDL-C >2.60 mmol/l and < or =4.20 mmol/l were stratified by ATV dose and randomised (1 : 1) to EZE 10 mg or PBO for 6 weeks while continuing open-label ATV. Significantly more patients achieved an LDL-C goal < or =2.6 mmol/l with EZE than PBO (81.3 vs. 21.8%; p < or = 0.001). Compared to PBO, co-administration of EZE with ongoing ATV led to significantly (p < or = 0.001) greater reductions in LDL-C, total cholesterol, triglycerides, non-high-density lipoprotein cholesterol (non-HDL-C), and apolipoprotein B; HDL-C was significantly (p < or = 0.05) increased. Co-administration of EZE and ATV was well tolerated, with an overall safety profile similar to ATV alone.